Baron Jons Jacob Berzelius (1779-1848), Swedish chemist. Berzelius was orphaned at an early age and brought up by relatives, attending school at Linkoping and university at Uppsala. He graduated as a physician and worked as a doctor, but also had a keen interest in chemistry. In 1807 he was appoointed professor of chemistry and pharmacy at the Karolinska Institute in Stockholm. In writing a book for his students he devised the law of constant proportions, in which inorganic compounds are made from different elements in strict proportion by weight. He produced the first accurate table of atomic masses for 28 elements, reintroduced initial letter symbols to label elements, devised the concepts of isomerism and catalysis and divided chemistry into organic and inorganic branches. He also discovered the elements selenium, cerium and thorium.